
where \(\psi ({\bf r})\)  and \(\varphi ({\bf r})\)  are the condensate modes associated with \(\vec{\eta }_+\)  and \(\vec{\eta }_-\) . One can check [1]}, [2]} that only \(\psi \)  is the critical mode with the divergent characteristic length and fluctuation het capacity at \(T \rightarrow T_{c0}\) . The fluctuations controlled by the mode \(\varphi \)  produce noncritical corrections and can be safely neglected. Thus, removing all the terms including \(\varphi \) , we arrive at the single-component Ginzburg-Landau functional
\(F =\int d^3{\bf r}\Big (a_\psi |\psi |^2 + \frac{b_{\psi }}{2}|\psi |^4 +\sum \limits _{i=x,y,z} {\cal K}^{(i)}_{\psi }|\partial _i\psi |^2\Big ),\) 
